Aptdec is a FOSS program that decodes images transmitted by NOAA
weather satellites. These satellites transmit constantly medium
resolution (4km/px) images of the earth over a analog mode called APT.
These transmissions can easily be received with a cheap SDR and
simple antenna. Then the transmission can be decoded in narrow FM mode.
The input audio format can be anything supported by libsndfile
(although only tested with WAV and FLAC). Sample rate doesn't matter,
although lower samples rates will process faster.
